Sound sources, adding

When two sound sources are added, it must be remembered that the decibel is a logarithmic unit. Therefore, they cannot be added arithmetically but must be combined as follows ... 

In adding synthetic harmonic Mid aharmonic components, it is important that die two components fuse perceptually [Hermes, 1991] i.e., that the two components are perceived as emanating from the same sound source. Through informal listening, sine-wave phase randomization appears to yield a noise component that fuses with the harmonic component of the signal. 

Difference Between Two Sound Sources (dB) Amount to be Added to Greater Sound Source (dB)... 

We used ultrasonic sound to rednce the size of emulsion droplets. For this purpose 10 (il of an aqueous solution was added to each ml of the organic solution. Sonication was executed using an Elmasonic S30H (Elma, Germany) sound source for 15 min at a temperature of 25 C. 

There are two approaches to fluid-generated noise control—source or path treatment. Path treatment means absorbing or blocking the transmission of noise after it has been created. The pipe itself is a barrier. The sound pressure level inside a standard schedule pipe is roughly 40-60 dB higher than on the outside. Thicker walled pipe reduces levels some at more, and adding acoustical insulation on the outside of the pipe reduces ambient levels up to 10 dB per inch of thickness. Since noise propagates relatively unimpeded inside the... 

Tw o noise sources produce 69.2 and 69 dB pressure levels respectively (Table 9.16) at the same space point. The composed sound at said point will have a total pressure level of 72.1 dB, calculated by adding 2.9 dB to 69.2 dB. In a similar way, at 250 hertz, for example, if each of the sources has a pressure level of 60 dB, the total level will be 63 dB (sum of 3 dB and 60 dB). 

The source of the electrons in the reduction of arsenic outlined in Fig. 7 is not known, but a sound model involving reduction by thiols has been proposed (133). A reexamination of Challenger s proposed methylation pathway looked at the effects of adding low levels of As(III), As(V), MMA, and DMA to cultures of two microorganisms including... 

The biorefinery approach is the most sound in terms of truly exploiting the potential of an aquatic biomass, and this concept is now becoming accepted on a worldwide basis. In the biorefinery approach, the economic and energetic value of the biomass is maximized, although it must be emphasized that fluctuations in the prices of fossil carbon (coal, oil, gas) raises uncertainty regarding the opportunity to produce biodiesel from aquatic biomass. For example, when the oil price is below US 120 per barrel it is uneconomic to produce biodiesel in this way. On the other hand, an aquatic biomass demonstrates an excellent potential for use as a source of specialty chemicals, with some components also having added value as animal feeds or fertilizers. 

Ironically, Pauling who was one of the few early authors to consider additional sources of magnetic anisotropy in aromatic hydrocarbons, was soundly criticised for adding these other contributions into his calculated anisotropies 27a>. 

Because of logarithmic scaling, sound pressure levels in decibels from two or more sources cannot be added arithmetically to determine the resulting sound pressure level. The data in Table 23-1 helps determine the resulting sound pressure level from two sources. It gives the relationship between the difference in decibels for two sources and the amount to add to the higher of the two sources. If there are more than two sources, add one pair of values at a time and add the third to the result of the first pair. Continue sequentially to account for all sources. 

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